Factors Determining Snowmelt in the Rocky Mountains

November 11, 2022

TomMC_EPOD.ColoradoRockiesSnowpack (004)

TomMC_EPOD.60.ColoradoRiverConditionsJuly2022 (003)

Photographer: Thomas McGuire 

Summary Author: Thomas McGuire  

Some 40 million people in the Southwestern United States depend, in a large part, on the Colorado River for agricultural and municipal water. About 90% of Colorado River water originates from melting snowpacks in the Rocky Mountains, such as shown on the photo above at Independence Pass, Colorado (taken in July 1977).

2021-2022 was a relatively decent year for snowfall in the Rockies, yet both major reservoirs, Lake Powell and Lake Mead, are at dangerous and historic low water levels. And they’re expected to continue to go down in the coming year.

With warming of the climate in the Southwest, the tree line has been creeping up mountain slopes. Trees lose water by transpiration from leaves and needles. Snow surfaces lose water by the process known as sublimation. Because trees absorb more sunlight than highly reflective snow, an early snowmelt exposes the dark soil, which absorbs more solar energy. Additionally, dust blown from the dry soil onto the snow makes the snow surface darker, absorbing even more sunlight and further contributing to earlier snowmelt -- see chart above. This confluence of factors is a challenge for the inhabitants of the Southwest. Fortunately, there are many alternatives allowing the residents to adapt to the “new normal.”


Independence Pass, Colorado Coordinates: 39.1086, -106.5640

Related Links:

Navajo Mountain and Lake Powell

Drought’s End at Provo River Falls

Author’s Earth Science Books